Non-rotatable fastener

ABSTRACT

A rotation resistant fastener for use in securing a plurality of members together includes a generally smooth shank portion having a plurality of radially projecting lobes extending lengthwise along the shank portion. Each lobe is arcuate throughout substantially its entire arc length and includes a high point of maximum radial projection located between a pair of low points of minimum radial projection. At one lengthwise end of each lobe there is an additional radial protrusion or bump that follows the contour of the lobe except that it projects further in a radial direction. In use, the fastener is inserted into aligned apertures in the members to be joined so that the radial bump urges the material around the apertures forwardly along the length of the hole and outwardly around the hole. The displaced material thereafter springs back toward its original position and packs around the lobes on the shank.

United States Patent Wilson et al.

[ 51 Aug. 29, 1972 [54] NON-ROTATABLE FASTENER [22] Filed: Dec. 31, 1969[21] Appl. No.: 889,546

[52] US. Cl. ..287/ 189.36 F, 161/4173 [51] Int. Cl ..Fl6b 5/02 [58]Field of Search .....151/68, 41.73, 22; 85/48, 46,

[56] References Cited UNITED STATES PATENTS 1,932,358 10/1933 Thomson..85/2l 1,972,119 4/1934 Wernhardt ..85/2l 2,024,071 12/1935 Taylor etal. ..85/21 2,613,570 10/1952 Sokolik ..85/21 430,236 6/1890 Rogers..85/48 3,455,198 7/1969 Barrett ..85/47 3,443,617 5/1969 Whiteside eta1 ..151/41.73

1,227,627 5/1917 Kennedy ..15l/4l.73

FOREIGN PATENTS OR APPLICATIONS 500,583 3/1954 Canada ..151/41.73

Primary Examiner-Edward C. Allen Attorney-Andrew L. Ney

[57] ABSTRACT A rotation resistant fastener for use in securing aplurality of members together includes a generally smooth shank portionhaving a plurality of radially projecting lobes extending lengthwisealong the shank portion. Each lobe is arcuate throughout substantiallyits entire arc length and includes a high point of maximum radialprojection located between a pair of low points of minimum radialprojection. At one lengthwise end of each lobe there is an additionalradial protrusion or bump that follows the contour of the lobe exceptthat it projects further in a radial direction. In use, the fastener isinserted into aligned apertures in the members to be joined so that theradial bump urges thematerial around the apertures forwardly alongthe'length of the hole and outwardly around the hole. The displacedmaterial thereafter springs back toward its original position and packsaround the lobes on the shank.

5 Claims, 4 Drawing Figures NON-ROTATABLE FASTENER use of matingthreaded fasteners to assemble semiblind joints, i.e., joints that areaccessible from both sides when inserting one of the fasteners intoaligned apertures in the joint, but which are accessible from only oneside when tightening the fasteners to clamp the joint, presents certainproblems. For example, when tightening the fasteners, it is necessary toprevent rotation of one fastener relative to the other and due to theinaccessibility of one side of the joint special fasteners and/or toolsare required. In addition to finding utility in semi-blind applications,these special fasteners and tools are utilized in various otherapplications where it is desirable to prevent rotation of one of thefasteners without gripping that fastener with a separate tool. Forexample, in assembly line operations and construction installations itis usually desirable for the workman to have both hands free to operatethe wrenching tool used to clamp the joint.

One type of fastener used in the above described applications includes abolt with a threaded portion spaced from the head of the bolt by knurledsection with sharp edges adapted to cut the surface of the apertures inthe members to be joined when inserted therein. While this type offastener generally prevents rotation of the bolt while the nut is beingtightened, it is relatively expensive due to the special operationrequired to form the knurls. Moreover, the joint is weakened due to thecutting of the surface of the apertures and, the stress concentrationsformed by the knurls in the members to be joined. Accordingly, this typeof bolt has limited application.

Another type of fastener used in the above described applicationsincludes a bolt having a shank with a smooth surface and a threadedportion. In addition, a broach is provided on the bottom surface of thepoint end of the shank and is engageable by a mating member on awrenching tool that also has a drive configuration. When assembling thejoint, the wrenching tool is placed in position on the bolt and itsassociated nut with the mating member engaging the broach on the shankand the drive configuration engaging the nut. When the tool is actuated,the bolt is held stationary and the nut is rotated to clamp the joint.While bolts of this type have generally been satisfactory in preventingrelative rotation with the nut, they are relatively expensive due to theextra length of material required in the shank to accommodate the broachand the special operation required to form the broach. Also, because ofthe special tools required, assembly of the joint is relativelyexpensive.

An alternative to using knurled or broach type bolts in semi-blind orsimilar joints is to clinch a nut in one of the members to be joined andthereafter tighten a bolt in the nut to clamp the joint. Since in mostapplications the bolt is tightened with a high torque, some mechanismshould be provided on the nut to prevent rotation of the nut in itsassociated member. One such mechanism for preventing rotation of the nutincludes serrations or teeth formed on the nut that embed in thematerial of the associated member when the nut is clinched thereto.While nuts formed with serrations or teeth are generally satisfactory inpreventing rotation with the member to which the nut is clinched, theserrations or teeth introduce stress concentrations into and weaken thejoint. Moreover, due to the special operation required to form theserrations or teeth, these nuts are relatively expensive.

It is an object of this invention, therefore, to provide an inexpensivefastener that is suitable for semi-blind applications.

It is still another object of this invention to provide an inexpensivefastener that will resist rotation when seated in a joint.

It is yet another object of this invention to provide a joint that isrelatively inexpensive to assemble when using a rotation resistantfastener.

These and other objects of this invention are accomplished by providinga fastener having a smooth shank portion formed with a plurality ofradially projecting lobes extending lengthwise along and arcuatelyaround the shank portion. Substantially the entire arc length of eachlobe is arcuate and includes a low point of minimum radial projection ateach end and a high point of maximum radial projection intermediate thelow points. The smooth shank portion may be tapered and each lobe mayfurther include an additional radial projection or bump that follows thecontour of its associated lobe except that it projects further in aradial direction. When the fastener is inserted into aligned aperturesin members to be joined, the radial bump forces the material around thealigned apertures forwardly along the axial length of the apertures andoutwardly in a radial direction. Thereafter, the material displaced bythe radial bump flows back toward its original position and packs aroundthe lobes on the shank. Accordingly, rotation of the bolt is prevented.

For a better understanding of the present invention, together with theobjects thereof, reference is made to the following description, takenin conjunction with the accompanying drawing, and its scope will bepointed out in the appended claims.

Referring to the drawings:

FIG. I is a perspective view of a bolt constructed in accordance withthe present invention;

FIG 2 is a plan view of the bolt shown in FIG. 1;

FIG. 3 is a'view in section taken along the line 33 of FIG. 2; and,

FIG. 4 is a view partly in section illustrating a bolt in accordancewith this invention inserted in a pair of panel members.

A preferred embodiment of a fastener in accordance with this inventionis disclosed herein the form of a bolt 10 having an enlarged-head 12, athreaded shank portion 14 and a generally smooth shank portion 16located between the head and the threaded shank portion. Head 12 may beof any suitable configuration and it will be understood from the furtherdescription of the preferred embodiment, may be omitted in various typesof fasteners. A recess, not shown, is provided in the head and isadapted to be engaged by a suitable wrenching tool in the event itbecomes desirable to assemble or disassemble the bolt from a joint byapplying a relatively high torque. As will also be clear from thefurther description of this invention, the bolt can be assembled anddisassembled in other ways and the recess may be omitted.

Extending substantially throughout the axial length of smooth shankportion 16 there are a plurality of radially projecting lobes 18, 20 and22 adapted to cooperate with the members to be joined, to preventrotation of the bolt. Each of the lobes is arcuate throughoutsubstantially its entire arc length so that each lobe comprises a pairof low points 24, that is, a point of minimum radial projection and ahigh point 26, that is, a point of maximum radial projection,intermediate the low points. It should be noted that each low point 24lies on the periphery of an imaginery circle, shown in dotted lines inFigure 3, located through shank portion 16 and as best seen in Figure 3,substantially all of the circumference of this imaginary circle, exceptfor the low points, has a lobular portion projecting therearound.

Located adjacent threaded section 14 on each lobe 18, 20 and 22, thereare a plurality of additional radial protrusions or bumps 28, 30 and 32,respectively, which facilitate insertion of the bolt into a joint. Thesebumps are arcuate throughout substantially their entire arc length andfollow the contour of their respective lobes, that is, they originatefrom the same low points, but project to a greater radial extent thanthe lobes and accordingly have a different high point. It should also benoted that shank portion 16 is slightly tapered with the greatercross-sectional area being located under the head and the smallercross-sectional area being located adjacent threaded portion 14. Thisslight taper also facilitates insertion of the bolt into a joint.

Referring to Figure 4, bolt is shown seated in aligned, circularapertures in a pair of panel members 34 and 36. The diameter of thealigned apertures in the panels is equal to the diameter of theimaginary circle defined adjacent the threaded portion 14 by the lowpoints of the lobes. Accordingly, bolt 10 must be forced into thealigned apertures and this may be accomplished in one of several ways.For example, an axial driving tool may be utilized to drive bolt 10completely through the apertures until the bearing surface of head 12bears on the outer portion of panel 36. Another method of inserting bolt10 into the aligned apertures comprises driving the bolt part way intothe apertures so that a portion of the lobes engage the material aroundthe apertures, placing a nut on the threaded shank portion 14 andthereafter tightening the nut so as to pull the bolt downwardly into theapertures until the bearing surface of head 12 abuts the outer surfaceof panel 36. The latter method permits hand installation of the bolt. Asthe bolt is forced into the apertures, radial bumps 28, 30 and 32 engagethe material around the apertures and force this material outwardly soas to enlarge the hole and forwardly toward the outer surface of panel34. When the bolt is seated, as shown in Figure 4, the materialdisplaced by the bumps springs back toward its original position, butwill pack around the lobes on shank 16 and especially in the low points24. Due to the lobular configuration of the shank, rotation of the boltis prevented while the nut is tightened. In addition, since the lobesengage panel 30 and a portion of panel 32, rotation of the panelsrelative to one another is prevented, however it should be understoodthat the lobes need only engage one of the panels, or can engage bothpanels throughout their entire thickness.

Still another method of inserting bolt 10 into aligned aperturesincludes the use of a wrenching tool that provides relatively hightorque for rotating the bolt, that is, a torque higher than thatnormally used to install and remove threaded fasteners. With this methodof insertion, the material around the aligned apertures is repeatedlydisplaced and sprung back toward its original position until therotation of the bolt ceases. At this point, the material around theapertures springs back and packs around the lobes in a manner similar tothat described in connection with axially inserted bolts. A primaryadvantage of this method of installation is that the bolt can beutilized with a tapped hole in a panel and the use of a nut is obviated.The resistance to rotation of the bolt provided by the cooperation ofthe lobes with the panel material provides a self-locking feature andprevents unintentional loosening of the bolt due to vibrations and otherexternal loads.

To remove the bolt from the joint, an axial driving tool can be utilizedto drive the bolt out of the panels. The bolt can be removed from thepanels upon the application of a sufficiently high torque, thusproviding an alternative method of removing the bolt in the event anaxial driving tool cannot be utilized.

At this point, it should be noted that by describing the lobes and bumpsas arcuate throughout substantially all of their arc length is meantthat at least a major portion of each protrusion is arcuate and anystraight line portions are minor. Such a configuration allows the highpoints of the lobe and bump to be located at points close enough to thecircle defined by the low points so that insertion of the bolt into thecircular apertures in the panels is facilitated while the desiredresistance to rotation is maintained. It should be understood that ifthe high points of the lobes are located too far from the imaginarycircle defined by the low points, an excessive amount of panel materialwill have to be displaced by the lobes and bumps and insertion of thebolt will be difficult, and in some cases impossible.

As pointed out previously, radial protrusions or bumps 28, 30 and 32facilitate insertion of the bolt into the apertures in the panels. Thisresults from the fact that the bumps do not extend over the entire axiallength of their respective lobes and during insertion of the bolt intothe apertures the bumps displace the panel material away from and out ofcontact with the lobes. By forcing the panel material out of contactwith the lobes, the friction between these members is reduced andinsertion of the bolt is facilitated. As also pointed out previously,the taper on shank portion 16 facilitates insertion of the bolt into theapertures.

A primary advantage of a fastener in accordance with this invention isthat no special operations are required to form the lobularconfiguration of the smooth shank portion, since this configuration canbe provided for in the dies of conventional machinery. Thus, the cost ofthe fastener is significantly reduced over that of knurled or broachtype fasteners.

Various modifications can, of course, be made to the preferredembodiment illustrated in the drawings. For example, the configurationof shank portion 16 can be utilized with nut, studs and other types offasteners. In addition, the number of lobes and their spacing may bevaried in accordance with various design requirements.

It should be clear from the preceeding description that a fastener inaccordance with this invention can be easily inserted in a joint so asto resist rotation therein without requiring the formation of specialhole that conform to the configuration of the shank portion of thefastener. In addition, since there are no sharp corners or edges on theshank portion of the fastener, no undesirable stress concentrations areinduced in the panel and, moreover, since the size of the apertures isincreased, a beneficial tensile stress is induced, dependent upon thelength of smooth shank portion 16, in one or more of the panel membersto be joined which adds to the fatigue strength of the joint.Furthermore, the fastener can be made without special manufacturingoperations that add to the cost and/or weight of the fastener. Finally,the joint can be assembled without the use of special tools.

While in the foregoing there has been described a preferred embodimentof the invention, various modifications may become apparent to thoseskilled in the art to which this invention relates. Accordingly, allsuch modifications are included within the intended scope of theinvention.

What is claimed is:

l. A rotation resistant threaded fastener comprising a shank portion,said shank portion including a threaded segment at one end and agenerally smooth portion at the other end of said shank, said generallysmooth portion comprising a tapered portion having a plurality ofprotuberances throughout substantially the entire axial length of saidgenerally smooth portion with each said protuberance being arcuatethroughout substantially its entire arc length and including acrosssectional shape of a high point of maximum radial projectionlocated between a pair of low points of minimum radial projection withsaid high and low points of radial projection having a progressivelyincreasing radial length along said tapered portion from a minimum foreach said minimum and maximum radial projections adjacent said threadedsegment of said shank portion to a maximum at the end of said shankportion remote from said threaded segment and a plurality of protrusionsof a finite axial length superimposed on said protuberances adjacent thejuncture of said threaded segment and said tapered portion with eachsaid protrusion being arcuate throughout substantially its entire arclength to follow the contour of an associated protuberance andprojecting radially outwardly further than said associated protuberanceat said juncture whereby when said fastener is operatively engagedwithin aligned apertures to fasten a plurality of workpieces togethersaid protrusions displace material of the workpiece around the aperturein said workpieces forwardly toward said threaded shank portion andoutwardly with the displaced material springing back toward its originalposition to pack about the protuberances on the tapered portion of saidshank to resist rotation of the fastener within the workpieces.

2. A fastener unit according to claim 1 wherein the low points ofadjacent protuberances are common.

3. A fastener unit according to claim 1 wherein an enlarged head isformed at that end of said shank portion opposite from said threadedportion.

4. A joint comprising a panel member having a hole extendingtherethrough,

and a rotation resist and threaded fastener tightly seated in said holein said panel, said fastener com prising a shank portion, said shankportion including a threaded segment at one end and a generally mooth 0on com ris'n ata ered 0 ion ha ing a pl rzil i ty of pr tu e rancethroiig out substantially the entire axial length of said generallysmooth portion with each said protuberance being arcuate throughoutsubstantially its entire arc length and including a cross-sectionalshape of a high point of maximum radial projection located between apair of low points of minimum radial projection with said high and lowpoints of radial projection having a progressively increasing radiallength along said tapered portion from a minimum for each said minimumand maximum radial projections adjacent said threaded segment of saidshank portion to a maximum at the end of said shank portion remote fromsaid threaded segment and a plurality of protrusions of a finite axiallength superimposed on said protuberances adjacent the juncture of saidthreaded segment and said tapered portion with each said protrusionbeing arcuate throughout substantially its entire arc length to followthe contour of an associated protuberance and projecting radiallyoutwardly further than said associated protuberance at said juncture,said fastener operatively engaged within said panel member so that saidprotrusions displace material of the panel member around the hole insaid panel member forwardly toward said threaded shank portion andoutwardly with the displaced material springing back toward its originalposition to pack about the protuberances on the tapered portion of saidshank to resist rotation of the fastener within the hole.

5. A joint according to claim 4 including a second panel member adjacentthe other panel member and having a hole aligned with said hole in saidother panel member, said shank portion of said fastener unit extendinginto said hole in said second panel member with said protrusions intightly fitted engagement with said second panel member, said materialin said second panel member compressed in the vicinity of said hole insaid second panel member as a result of said protrusions having greatercross-sectional dimensions than the size of said hole in said secondpanel member prior to installation of said fastener unit.

1. A rotation resistant threaded fastener comprising a shank portion,said shank portion including a threaded segment at one end and agenerally smooth portion at the other end of said shank, said generallysmooth portion comprising a tapered portion having a plurality ofprotuberances throughout substantially the entire axial length of saidgenerally smooth portion with each said protuberance being arcuatethroughout substantially its entire arc length and including across-sectional shape of a high point of maximum radial projectionlocated between a pair of low points of minimum radial projection withsaid high and low points of radial projection having a progressivelyincreasing radial length along said tapered portion from a minimum foreach said minimum and maximum radial projections adjacent said threadedsegment of said shank portion to a maximum at the end of said shankportion remote from said threaded segment and a plurality of protrusionsof a finite axial length superimposed on said protuberances adjacent thejuncture of said threaded segment and said tapered portion with eachsaid protrusion being arcuate throughout substantially its entire arclength to follow the contour of an associated protuberance andprojecting radially outwardly further than said associated protuberanceat said juncture whereby when said fastener is operatively engagedwithin aligned apertures to fasten a plurality of workpieces togethersaid protrusions displace material of the workpiece around the aperturein said workpieces forwardly toward said threaded shank portion andoutwardly with the displaced material springing back toward its originalposition to pack about the protuberances on the tapered portion of saidshank to resist rotation of the fastener within the workpieces.
 2. Afastener unit according to claim 1 wherein the low points of adjacentprotuberances are common.
 3. A fastener unit according to claim 1wherein an enlarged head is formed at that end of said shank portionopposite from said threaded portion.
 4. A joint comprising a panelmember having a hole extending therethrough, and a rotation resistantthreaded fastener tightly seated in said hole in said panel, saidfastener comprising a shank portion, said shank portion including athreaded segment at one end and a generally smooth portion comprising atapered portion having a plurality of protuberances throughoutsubstantially the entire axial length of said generally smooth portionwith each said protuberance being arcuate throughout substantially itsentire arc length and including a cross-sectional shape of a high pointof maximum radial projection located between a pair of low points ofminimum radial projection with said high and low points of radialprojection having a progressively increasing radial length along saidtapered portion from a minimum for each said minimum and maximum radialprojections adjacent said threaded segment of said shank portion to amaximum at the end of said shank portion remote from said threadedsegment and a plurality of protrusions of a finite axial lengthsuperimposed on said protuberances adjacent the juncture of saidthreaded segment and said tapered portion with each said protrusionbeing arcuate throughout substantially its entire arc length to followthe contour of an associated protuberance and projecting radiallyoutwardly further than said associated protuberance at said juncture,said fastener operatively engaged within said panel member so that saidprotrusions displace material of the panel member around the hole insaid panel member forwardly toward said threaded shank portion andoutwardly with the displaced material sPringing back toward its originalposition to pack about the protuberances on the tapered portion of saidshank to resist rotation of the fastener within the hole.
 5. A jointaccording to claim 4 including a second panel member adjacent the otherpanel member and having a hole aligned with said hole in said otherpanel member, said shank portion of said fastener unit extending intosaid hole in said second panel member with said protrusions in tightlyfitted engagement with said second panel member, said material in saidsecond panel member compressed in the vicinity of said hole in saidsecond panel member as a result of said protrusions having greatercross-sectional dimensions than the size of said hole in said secondpanel member prior to installation of said fastener unit.